Impromptu, Gb Major, Op 90 No.3

[melia]

Does anyone have any tips or exercises to learn on how to play this piece well? I thought I'd give it a try as it sounds deceivingly simple. How WRONG I was! My right hand is giving me trouble, especially those inner running notes. Should they be played softly and evenly so the melody can be heard? When I play slowly, they are either too loud or harsh, but when I speed up, some of them are inaudible! Either way the melody is totally ruined! HELP! I have been practicing this piece for over 4 months (don't laugh) now, but I'm still not happy with it. I love this piece for it's beautiful melody but I find it the most challenging, and is really testing my patience!  Has anyone really mastered this piece, what tips can you give?? I HAVE to get it right!